A source familiar with the tower’s “antiquated” internal condition also suggests TIAA is reluctant to commit an estimated $40 million to $50 million “to bring it into the modern world.”

A second source said, “The building needs a lot of work. Its electrical system is a mess.”

No one involved in the prospective sale offering was in any position to talk about it. No “for sale” announcement is expected.

“Nobody wants to cross Teachers’,” one industry player said of the powerful fund that manages some $290 billion in assets. But TIAA has quietly tapped Insignia/ESG, the building’s managing agent, to consider offers.

Since selling the tower to TIAA in 1979, Seagram has continued to maintain its headquarters in the building, where its roughly 190,000 square feet make it the largest tenant.

It was not immediately clear what impact, if any, Seagram’s merger with Vivendi would have on its need for space in the tower.

In any event, the building’s most famous tenant is surely the Four Seasons – the magnificent restaurant designed by Philip Johnson, the collaborator of Mies van der Rohe, the building’s architect.

Other large office tenants include Unicredito Italiano, with 30,000 square feet, and KDD America, with 23,000. Seagram is also home to some tenants with as little as 4,000 square feet – among them, the National Association of Stock Car Racing (NASCAR) and small investment banks to whom a Seagram Building address lends prestige.

Many of those smaller leases are turning over in the next few years, creating an opportunity to replace them with large-block users who would pay a premium.

The few blocks of available space are asking between $85 and $100 a square foot.

The building’s landmark status means that any improvements may be more expensive. Not only the tower’s exterior, but its lobby and the public plaza are landmarked as well.

So is the Four Seasons. Although TIAA actively sought landmarking for the tower, it opposed landmarking the restaurant.

TIAA argued that, “designation of the sculpture, artwork, metal drapes, decorative railings, and bar … clearly restricts our rights as owner to use this space in the future for anything than a restaurant.”

The plaza, with two reflecting pools, is under reconstruction. “They’re re-waterproofing the entire plaza area,” said Landmarks Commission spokesperson Katy McNab. “And they’re putting everything back in place when it’s done.”

Two years ago, RFR Holding bought the leasehold of another landmark 1950s office building diagonally across the avenue from Seagram – the 1953 Lever House at 390 Park – and is spending a fortune on modernizing the structure in conformity with landmark law.